A hydrostatic transmission (HT) is a known technology that transfers power from a power source (typically an engine) to a power utilizer (typically a portion of a vehicle). The major components of the HT are a traction pump, one or more traction motors and a hydraulic circuit. The hydraulic circuit enables fluid communication between the pump and the motor(s).
It is also known that if one or more hydraulic accumulators are added to the vehicle and fluidly connected to the hydraulic circuit, the vehicle gains the capability of storing and re-injecting hydraulic energy, and may be commonly described as a series hybrid system (SHS).
A transition of the vehicle from using the HT to becoming an SHS is enabled by a powerboost hub, which is able to fluidly connect the hydraulic accumulator(s) to the hydraulic circuit and to disconnect the hydraulic accumulator(s) from the hydraulic circuit.
Due to the differences in hydraulic pressure that may exist between the hydraulic accumulators on one hand and the hydraulic circuit on the other, fluidly connecting the hydraulic accumulators to the hydraulic circuit may cause mechanical jerks. Disconnecting the hydraulic accumulators from the hydraulic circuit may have similar effects due to the resulting change in hydraulic power fed to the hydraulic circuit. However, these mechanical jerks are generally undesirable since their occurrence may impair the controllability of the transmission and cause increased wear of mechanical components.